If you're interested in ring theory, for example, Kummer's 1844 manuscript on "ideal complex numbers" clarified a bunch of undergraduate algebra for me. Overv

If you're interested in ring theory, for example, Kummer's 1844 manuscript on "ideal complex numbers" clarified a bunch of undergraduate algebra for me. Overviews: https://projecteuclid.org/journalArticle/Download?urlid=bams%2F1183539459 https://projecteuclid.org/journalArticle/Download?urlid=bams... https://arxiv.org/pdf/1108.6066.pdf https://arxiv.org/pdf/1108.6066.pdf